Hail Resistance of Roofing ProductsBuilding Research Division, U.S. Institute for Applied Technology, 1969 - 9 pages A test was developed for evaluating the hail resistance of roofings, in which synthetic hailstones (ice spheres) of various sizes were shot at roof assemblies at their free-fall terminal v * elocities.Indentations, granule loss and roofing fracture were observed.The principal conclusion is that:All roofing materials have some resistance to hail damage, but as the size of the hail increases, a level of impact energy is reached at which damage occurs.This level lies in the range of 1 1/2 to 2 inch (3.8-5.1 cm) hailstones for most prepared roofings.(Author). |
From inside the book
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Page 1
... freezing point and remains subcooled until it encounters a nucleus upon which to freeze . As more water hits any par- ticular ice particle , the particle grows . Because everything in these upper regions is at a tem- veloped . It was ...
... freezing point and remains subcooled until it encounters a nucleus upon which to freeze . As more water hits any par- ticular ice particle , the particle grows . Because everything in these upper regions is at a tem- veloped . It was ...
Page 2
... freezing point of water , the ice that forms does so rapidly and traps air in the process . This forms a milky layer of low - density ice . When an ice particle becomes too heavy to be raised farther by the updraft , it starts to fall ...
... freezing point of water , the ice that forms does so rapidly and traps air in the process . This forms a milky layer of low - density ice . When an ice particle becomes too heavy to be raised farther by the updraft , it starts to fall ...
Page 3
... freezes , subcools and goes through its tumbling cycle over and over again . Thus , the hailstone is found to consist ... freezing and tumbling processes occur and then the hailstones drop out as in the frontal storm . This type of storm ...
... freezes , subcools and goes through its tumbling cycle over and over again . Thus , the hailstone is found to consist ... freezing and tumbling processes occur and then the hailstones drop out as in the frontal storm . This type of storm ...
Page 4
... freezing com- partment of a conventional refrigerator . Four hours later water was added to fill the mold just to the bottom of the gate and the mold was returned to the freezer . Only by this two- stage process was it possible to freeze ...
... freezing com- partment of a conventional refrigerator . Four hours later water was added to fill the mold just to the bottom of the gate and the mold was returned to the freezer . Only by this two- stage process was it possible to freeze ...
Common terms and phrases
15 cents air gun apparatus Applied Technology areas of different Asbestos cement asphalt flood coat Asphalt Roofing asphalt shingles automatic data processing building damage Building Research Building Science Series Built-up roofs Bureau of Standards Cement and Concrete Center Class C shingle Coal tar Concrete Properties cracking cylinder dense decks dents DEPARTMENT OF COMMERCE diameter different vulnerability felt damage Fiberboard on 1-in Foamboard free-fall terminal velocity freezing ft 61 cm Gas cylinder Glass fiber insulation hail damage hail resistance hailstone carrier Hailstone Molds Hailstorms ice spheres indentation Institute for Applied interply asphalt Interrelations Between Cement Joules kg/m² kg/m³ large hailstones launcher lb/sq Meteorol microswitches National Bureau Nonbituminous Roofing organic felt polyethylene Portland Cement prepared roofings reported Resistance of Roofing resistant to hail shingles showed Sidney H sizes of hailstones slag solidly supported areas specimen steel decking substrates tested Type 235 shingles U.S. DEPARTMENT U.S. Government Printing velocity 9 ст